The loading or emptying of a container such as a reserve container, silo, bunker or an autoclave or an inlet unit of a pneumatic or hydraulic conveyor system, with a charge in the form of fluid loose material, viscous deposits, sludges or the like, presents special difficulties when such charge is still only to be placed in batches and the container is to be sealed tightly again between two insertions, this charge, however, having a great wear effect on the components belonging to the inlet opening and to the sealing device. It has become clear that particularly in the case of materials which already have a great wear effects in the cold state such as quartz sand, for example, unfavourable signs of wear usually appear on the components of the sealing device of the container, which take part with each other in the sealing effect, already after a relatively short period of operation, which signs of wear nullify a good sealing effect for the container and either force adjustment and readjustment operations on the sealing device or the exchange of the components of the device which take part with each other in the sealing effect. In the light of experience, however, the two measures require a not inconsiderable expenditure of time and work, quite apart from costs thereby occasioned not only for the provision with regard to the necessary amouring of parts subject to such a wear effect and the increased warehousing and operating costs for keeping and assemblying spare parts but also in so doing a more aggravating disadvantage occurs which is to be considered the fact that for each such maintenance or exchange procedure the operation of the system to which the container belongs as a unit that is connected to the input or the output, must be interrupted, which in the overwhelming number of cases of use usually leads to considerable operational shutdowns.
These problems are aggravated more substantially if the charge not only shows a great wear effect which derives from its grain configuration and its hardness as well as its abrasive resistance, but has additionally or alternatively thereto an agressiveness which derives from its chemical properties or from its temperature at which it is passed through the inlet opening of the container. Such behavior results, for example, when the charge, for example, is hot plaster of Paris or a final or intermediate manufactured product of the chemical industry, particularly of the plastics industry. In such cases the components of the sealing device which apply the sealing action for the inlet opening of the container suffer not only from the mechanical wear due to abrasion but also due to caustic and corrosive effects of a chemical nature and the like on the one hand and on the other hand alteration phenomena because of high temperature stresses not only in constant operation but also frequently moreover temperature cyclic stresses.
And this unfavorable mechanical, chemical and temperature stress behavior have further as well an even more unproportionally unfavorable effect when the frequency of loadings which is to be made equal with the switching frequency of the sealing device for the inlet opening of the container, increases. This is predominantly the case when the container is operated as a storage unit for a hydraulic or pneumatic conveyor system for the charge in which it is vital that this charge after having been inserted in the container by the application of an increased pressure is to be further conveyed in a fluidized or an air pressure compressed state, which has as a precondition that one ensures that this pressure cannot leak out from the interior of the container. This however means the necessity of ensuring and maintaining a secure and reliably pressure-tight sealing of the inlet opening of the container. On the other hand problems of an identical kind, however, also occur when the container comes to be used not in conjunction with a hydraulic or pneumatic conveyor system but one only has to ensure that certain pressure ratios and/or conditions are maintained in its interior with respect to the composition of the container contents. This may, for example, be the case when a charge of the kind described is to be kept in the container under inert gas conditions and one has to prevent in a reliable manner gaseous or fluid media, which enter into a chemical reaction with the charge, from penetrating into the container interior as, for example, in the case of an inflammable charge, oxygen which leads to the ignition of the charge.
The problem that the inlet opening of a container must be sealed on the one hand tight with respect to the charge and on the other hand pressure-tight has already been recognized. For this solution a design of sealing device for an inlet opening or a pressure vessel, used as a feed unit for a pneumatic conveyor system, has also already become known in which the sealing of the inlet opening of the vessel takes place in two stages. In this design there projects into the inlet opening of the container annularly on all sides a rubber gasket having a trapezoid cross-section and two shear edges, one lying above the other as well as a sealing seat which is connected to the lower shear edge and broadens inward in the direction of discharge to the interior of the container in the fashion of a cone or of a truncated cone. A sealing element operates against this sealing ring which is contoured to a sharp edge from the interior of the container outwards and has a butting face for the charge, which has the shape of a truncated cone and is rounded off in its culmination area and continues in the lower area to a cylindrical step having a diameter which deviates slightly from the internal diameter of the sealing ring and then continues outwards and downwards to a sealing surface which has a truncated cone shape corresponding to the truncated cone-shaped sealing surface of the sealing ring and is brought to abut the opposing face of the sealing ring in an areal manner in the course of the sealing movement of the sealing element.
In this known device the upper shear edge of the sealing ring, which determines the shape of the charge column, following the movement of the sealing element, and the wall of this sealing area are subject to an increased wear. This results, already in the course of a relatively short operational period, in wear, which can neither be foreseen nor controlled, of the edges which are necessary for the sealing effect of the known device.
From fundamental considerations, which are confirmed by experience, in the case of this known device a pressure tightness can also, however, already not be achieved as before and is not at all to be ensured for longer operational periods. In fact it is unavoidable in this case that particles of the charge lodge between the corresponding conical sealing surfaces of the sealing element and the sealing ring and prevent a good and tight abutting of the surfaces on one another.
The object of the invention is to produce by simple and cheap means, avoiding the disadvantages of known methods, a possibility of loading the container with or emptying it of, through an opening in its top or bottom wall, fluid loose material, viscous deposits, sludges or the like, without taking into account physical or chemical properties of such a charge, as, for example, its particle configuration, distribution of grain size, hardness properties, degree of humidity, temperature, chemical aggresiveness and the like, in batches or also with a high batch frequency or high switching frequency of the sealing element sealing off the inlet opening of the container, and after loading or emptying of being able to seal it tightly again, in such a manner that not only a maximum low-wear sealing with respect to the charge is always reliably ensured but also a secure and lasting pressure sealing over long operational periods, whereby moreover this possibility should be effectively present even with containers containing an excess pressure with respect to the ambient pressure without additional and costly measures for remotely controlled pressure venting even if the container when its inlet opening is being fed, is to be loaded at substantial height and under normal pressure conditions without a charge column being stored above the opening.
The object is achieved in accordance with the invention in that the sealing element has a sealing surface which can be brought into linear sealing abutment with a sealing seat, secured to the wall, and in that above this line of sealing abutment a casing with a diameter smaller than that of the sealing abutment line is supported at rest on the sealing surface of the sealing element during the first part of the opening operation and is kept free in the following movement and in that a guide device is provided for the charge by means of which it can be guided onto the area of the sealing element, which is enclosed by the casing, resting on the sealing surface of the sealing element.
In the case of a device in accordance with the invention the column-shaped charge is fed from an upper height level, whilst maintaining its floor pressure surface support, past the lower height level of the sealing seat in such a manner that there is no possibility of coming into contact with it when the charge according to its angle of pouring or of flow is presented with the possibility of freely sliding down along the peripheral contours of the sealing surface of the sealing element. Thus the concept in accordance with the invention cannot lead to the undesirable disadvantages of known solutions, as in accordance with the invention the sealing off of the charge flow with respect to the sealing element is not only separated from the pressure sealing but it is ensured in accordance with the invention that any contact between the charge and the sealing seat intended for a satisfactory pressure sealing is excluded.
It is proposed in accordance that the sealing element is constructed in such a manner it constantly widens the free cross-section of passage for the charge during the course of its opening movement. Thus in fact by extremely simple and cheap means any bridge formation between the guide device and the sealing surface of the sealing element on the one hand and the floor pressure surface of the charge on the casing, limiting the sealing surface of the sealing element, and the sealing surface of the sealing element on the other hand is avoided.
The casing can, if required, be kept in abutment on the sealing surface of the sealing element, but it has, surprisingly, been shown that this is not at all necessary in many cases and it is moreover sufficient if the casing is kept at rest through the effect of gravitational forces, i.e. on the sealing surface of the sealing element. It has thereby proved particularly advantageous that the casing, in accordance with the invention, can be kept, during the opening movement of the sealing element, in abutment on the sealing surface of the sealing element due to the effect of friction on it of the charge contained between it and the sealing element.
Ad advantageous combination of the favorable starting and sliding effect for the charge of a conical construction of the sealing surface of the sealing element with the particularly favorable self-adjusting effect of a construction of the sealing face having the shape of a spherical segment, is achieved in accordance with another inventive development in that the sealing element has a sealing surface composed of a conical culmination area and an area, having the shape of a spherical segment, which is connected to it towards the outside and opposite which the casing is supported, and/or an area, having the shape of a spherical segment and connected outwards, which can be brought into sealing abutment with the sealing seat, secured to the top wall.
In accordance with the invention the casing is brought during the opening movement of the sealing element from a closing position, located above the sealing seat, to a protective position which overlaps the sealing seat on its inner side at a distance in the manner of a curtain. It is important that the discharged material slides freely past the sealing seat according to its angle of pouring or flow.
A particularly simple and cheap design is achieved in that in accordance with a further inventive development the casing for the raising and sinking movement is guided laterally on the top wall. In so doing the casing can preferably be guided during its movement which follows the raising and sinking movement of the sealing element with a degree of freedom for a tipping or tumbling movement with a slight angle of inclination to the direction of movement of the sealing element. The casing thus in fact obtains in accordance with the object to a greater extent the possibility of adjusting itself, independently of the nature of the charge stream, to the sealing surface of the sealing element, and of being able to adapt to it in such a manner that an optimal sealing effect with respect to the charge particles is always ensured. For this purpose the casing can, in a further advantageous development of the invention, have distributed at uniform angular distances radially about its outer surface guide ribs which project therefrom, whose front faces are guided along the inner wall of a socket, secured to the top wall, for axial movement. An embodiment which is to be preferred for both design as well as production reasons is thereby achieved when a movement equalization clearance is provided for the casing between the front faces of the guide ribs and the socket. Furthermore to further improve the sealing effect the casing can have in its lower peripheral area an inner diameter which widens outwards. Its expanded part can for this purpose can thus be constructed in the shape of a cone.
The self-adjusting action of the casing relative to the sealing surface of the sealing element is increased still further by simple and economical means in that the guide ribs are rounded off in their end at their end regions and moreover their leading edge area is tapered outwards. In addition the guide ribs are supported advantageously in order to limit the axial movement of the casing and thus to end the lateral guidance of the charge column which rests on the central area of the sealing surface of the sealing element as a floor pressure surface and to release the free sliding down of the column in that they are constructed as a stop cam which abuts on the stop surface of the top wall. This effect is further supported in that the end regions of the guide ribs are rounded off. In so doing any wear which could, in fact, occur due to the guide ribs striking the stop cams at the side of the top wall, is kept to a minimum, whereby moreover an impact height which always remains the same, remains ensured even if the casing should once adopt an equalization position which is tilted at a slight angle of inclination to the direction of movement of the sealing element.
In accordance with an inventive development the sealing element at least during its abutting of the sealing seat is kept with a degree of freedom for a tipping or tumbling movement about its axis of movement. This can be effected advantageously by a single-point suspension of the sealing element. In so doing the sealing element is left the possibility of adjusting itself optimally depending on the operational parameters relative to the casing, determining the effective flow surface for the charge and/or the sealing seat, cooperating with its sealing surface, in such a manner that with the least possible wear effect a tight abd reliable pressure sealing is always possible.
A further inventive idea is directed towards the exclusion of any bridge formation by the charge in a reliable manner. In accordance with this inventive idea a loosening pulse can be applied in accordance with the invention during the course of the opening movement of the sealing element after it lifts away from the sealing seat, to the accumulation of charge between the sealing element and the casing, resting on it, and/or to the sealing element and/or the wall area adjacent to the sealing seat. Both can be effected in an inventive development of this inventive idea in that the loosening pulse can be applied by an impact of a striking member, secured to the casing, on the wall area near to the sealing seat. For this purpose, when the sealing device in accordance with the invention has a casing, guided by way of radial guide ribs, for the limitation of the floor pressure area or the charge accumulation resting thereupon, the guide ribs, secured to the casing, can be called upon, in that the loosening pulse can be applied to their lower ends as striking members which strike a stop nose or rim disposed so as to be secured to the top wall.
In this manner by extremely simple and cheap means any kind whatsoever of bridge formation is also effectively excluded under unfavorable conditions and when the charges possesses properties which are difficult to overcome. Furthermore still during the course of the cycle of the method in accordance with the invention, any bridge formation is effectively prevented in that in fact the limiting or ending of the sinking movement of the casing is used in order to apply a loosening pulse automatically i.e. by the impact of the guide ribs, constructed as striking members, of the casing on a stop nose or rim on the top wall of the container to be loaded.
In accordance with a further proposal concerning the invention loosening pulses are also applied during the course of the closing movement of the sealing element.
It is basically immaterial to the invention how the cross-section of the sealing seat is constructed if one only ensures that the pressure sealing takes place by way of a linear contact between sealing surface of the sealing element and the sealing seat and not, as in the prior art, by means of the abutment of two corresponding sealing surfaces on each other. It has, however, proved to be particularly advantageous if the sealing seat is formed by a ring seal of an elastic material, which is kept in the inner front wall of the inlet opening. By this means a certain self-adjustment of both sealing elements which effect the pressure sealing is in fact reached. This can be even further increased in that the cross-section of this ring seal has, at least in the sealing area, a constant convex curved peripheral contour.
A further development of the invention has proved to be advantageous both from a design and production standpoint as well as with regard to ease of assembly, in accordance with which the sealing element is mounted at the end of a piston rod of a hydraulically or pneumatically actuatable cylinder which is kept in the interior of the container by way of spacer bolts which project into the container interior from the top wall. In so doing it is advantageous if at least two of the spacer bolts can be constructed as feed or discharge pipes for the hydraulic or pneumatic pressure means.
This concept in accordance with the invention offers for the first time the possibility, in inserting the charge in the container intended for its reception, of being able to dispense with additional devices for removing air from the container, which devices are otherwise required and in the majority of ceases are associated with not inconsiderable costs. Particularly when it is the case that the container, to be loaded, contains a gaseous filling medium, it is an economically important factor in the vast number of cases if there is a possibility of not simply blowing off this filling medium but of making it accessible for further use. For this purpose the basic concept in accordance offers the possibility during loading of discharging the air in the container, displaced by the charge. In the csse of a surprisingly simple and cheap inventive development which depends on this basic concept in accordance with the invention it is an essential feature that the displaced air of the container to be loaded can be discharged by means of the peripheral part of the inlet opening, not filled out by the incoming charge, between the sealing seat and the charge stream in counter-flow thereto. It can be recognized that by this means many technical advantages, which hitherto were unattainable, can be achieved.
In the prior art it is further completely impossible to insert a charge in a closed receiving chamber or a container, which is to be loaded, in whose interior prior to insertion of the charge the air is under excess pressure with respect to ambient pressure. Here the dual flow concept in accordance with the invention offers the possibility of effecting the necessary equalization of pressure while maintaining the other advantages achieved in accordance with the invention.